Computer control of hydrocarbon conversion



Oct. 19, 1965 R, G. ATKINSON ETAL 3,213,014

COMPUTER CONTROL OF HYDROCARBON CONVERSION Filed June 14, 1962 2 Sheets-Sheet 2 3,213,014 Patented Oct. 19, 1965 United States Patent Office 3,213,014 COMPUTER CONTROL OF HYDROCARBON CONVERSION Robert G. Atkinson and Ernest D. Tolin, Bartlesville,

Okla., assignors to Phillips Petroleum Company, a

corporation of Delaware Filed .lune 14, 1962, Ser. No. 202,531 Claims. (Cl. 208-113) This invention relates to a method and apparatus for automatically measuring hydrocarbon conversion and controlling the depth of cracking thereby in the fluidized catalyst cracking of petroleum oils.

The feasibility of applying computer systems to the cont-rol of continuous chemical processes is finding growing acceptance. Generally, various process measuring instruments feed data directly and automatically to the computer and the computer carries out previously specified calculations. Based on these calculations, adjustments in the settings of process control instruments are made for optimum performance of the unit process.

As applied to petroleum refining processes, and to the operation of fluid catalyst crackers, in particular, much remains to be done to realize the potential improved performance from computer control of process variables. One of the major variables or operating guides in catalytic cracking is hydrocarbon feed conversion, or depth of cracking, taking place in the riser of a catalytic cracking reactor. Present systems of instrumentation fail to give indication of conversion, the latter being dependent upon several factors, principally: (l) coke on the catalyst, (2) metal on the catalyst, and (3) sintering of the catalyst particles from overheating. It thus appears that if hydrocarbon conversion could be measured operationally, it would give a good index of overall cracking system activity.

We have discovered a means of determining the initial rate of conversion in the riser of a reactor, which is a measure of catalyst activity. According to our invention, we achieve this primarily by determining the total heat content of all materials passing into a catalytic reactor at a given cross-section near the bottom of the riser thereof. The total heat content, after intimate mixing of these materials, is also determined at a second point in the riser near the top thereof. The difference in these two values is equal to the heat absorbed by the cracking reaction, the heat loss from the riser and the work done by expansion of gas in the riser. The heat absorbed by the cracking reaction is divided by the product of feed hydrocarbon rate and heat of reaction per pound of hydrocarbon to obtain feed oil conversion, or depth of cracking occurring in the riser. By logging the aforedescribed process variables automatically, transducing them for input to a computer, the computations can be made therein automatically. A control signal is produced which is applied to regulate a motor valve that admits regenerated catalyst into the riser of the reactor, thereby permitting control of the depth of cracking. Alternately, the control signal may be used to manipulate the supply of air or oxygen to the regenerator so as to control catalyst activity. This signal may adjust both simultaneously.

The objects of our invention are: to provide a method of and apparatus for automatic control of depth of cracking in a fluid catalytic cracking unit by using an analog computer; to provide a method of and apparatus for monitoring hydrocarbon conversion using an analog computer in cooperation with a catalytic cracking process; and to provide automatic and continuously controlled regenerated catalyst flow to the riser, and control of the air rate to the catalyst regenerator,

Other objects, aspects, and the several advantages of the invention will be apparent from a study of the disclosure, the drawing, and the appended claims.

FIGURE 1 is a block diagram of a uidized catalytic cracking reactor, regenerator, and main fractionator, in combination with a heat balance computing analog computer for controlling regenerated catalyst ow rate to the reactor. i

FIGURE 2 illustrates a schematic diagram of elements or components of a heat balance computing network which can be employed in the control system illustrated in FIGURE l.

Reference is now made to the drawing, and to FIGURE 1 in particular, wherein there is shown a fluid catalytic cracking reactor 11 having a mobile or uidized bed of solid particles 12 disposed therein. A catalyst regenerator 13 has a uidized bed 14 therein, the level of which is maintained approximately constant by periodic addition of fresh catalyst. The regenerated catalyst overflows into internal outlet conduit 16, from whence it passes through a motor-actuated slide valve 17, and is fluidized in transfer conduit 18 before entering reactor 11. The temperature of the hydrocarbon materials in the reactor, specically the reactor bed, or the dense phase mixture of hydrocarbon vapor, steam, and catalyst particles, can vary. This temperature TR, being sensed by thermocouple 19 disposed therein, connects through transducer 20 to temperature recorder 20a.

Slide valve 17 in transfer conduit 18 is operatively connected with a conversion controller 23. Thus, in accordance with the set point 21 on said conversion controller, a greater or lesser quantity of hot regenerated catalyst is adrnixed with the hydrocarbon feed materials and steam, entering the transfer conduit 18, via conduits 24 and 25, with the reactor temperature, and the depth of cracking being thus regulated. Reactor bed 12 may comprise a mixture of catalytic particles and non-catalytic solids uidized by hydrocarbon vapors and steam. A stream of spent catalyst material is withdrawn from bed 12 via internal conduit 26, and then stripped by steam added through conduit 31 for oil removal. Then the stripped, coke-laden catalyst passes through another motor-actuated slide valve 32, which is manipulated by level controller 33, in accordance with the set point thereof, and the level measurement produced by differential pressure transmitter 34, dropping the catalyst into transfer conduit 36, where it is picked up by the regeneration air, and conveyed into the bottom of regenerator 13. Air is supplied at a controlled rate via conduit 37 to conduit means 36. Regeneration of the catalyst by the input air in fluidized bed 14 takes place at a temperature preferably between 950 and 1200 F.

The spent gases from combustion of the carbonaceous solids disposed on the catalyst, pass therefrom through a cyclone 38, and outlet conduit 39. Products from reactor 11, in vapor form, pass upwardly through cyclone 41, and outlet line 42, to suitable recovery apparatus such as fractionator 43, and the subsequent separation system.

Feed conduit 24 supplies a combined stream of hydro carbon feed materials, to transfer conduit 18, to be catalytically cracked in reactor 11. There is disposed therein an orifice assembly and transmitter 44, the resulting signal therefrom, designated APO, being readily correlatable with hydrocarbon material flow rate. The resulting transduced signal from transmitter 44 is transmitted to a feed material flow rate and heat balance computing network 46, via signal line 47.

Superheated steam feed line 25 has disposed therein an orifice assembly and transmitter 4S, the resulting signal, designated APS, therefrom being readily correlatable with ow rate, this transduced signal also being transferred to i computing network 46 via signal line 49.

Transfer conduit 18 also has disposed therein two pressure sensing means SOL and 50u and transmitter 51. The differential signal therefrom, designated APT, makes it possible to calculate the total feed material ow rate. The resulting transduced signal is transmitted to computing network 46 via signal line 52.

The temperature of the combined feed materials in the upstream or lower portion of the riser, designated TL, is sensed by thermocouple 53 disposed therein. Thermocouple 53 connects through transducer 54 and line 56 to com-puting network `46.

The temperature of the total feed materials in the downstream or upper portion of the riser, designated TU, is sensed by thermocouple 57 disposed therein. Thermocouple 57 connects through transducer 58 and line 59 to computing network 46.

Feed conduit 61 supplies a hydrocarbon material, to be cracked which may be an unvaporizable hydrocarbon, to oil feed conduit 24. Feed conduit 61 is provided with a tube-type preheat furnace 62, which is heated by combustion of fuel gas entering through conduit 63. Also disposed in conduit 61 is a motor Valve 64 which regulates the flow of the virgin gas oil into the system.

' Referring again to main fractionator 43, two product streams are removed as side draws. The `streams are: light cycle oil stream 66, and heavy cycle oil stream 67. Main fractionator bottoms stream 68 directs nonconverted -oil and recovered catalysts back to feed conduit 24, in accordance with liquid level in the bottom of main fractionator 43, as sensed by level controller 69. Conduit 71 communicates between heavy cycle oil conduit 67 and bottoms slurry conduit 68. Motor valve 72 controls the flow through conduit 71, as directed by flow recorder controller 73, which is connected with turbine flow meter assembly 74 disposed in conduit 68. Gas and gasoline products pass overhead from main fractionator 43, via conduit 76, to separation vand recovery equipment (not shown).

Computing network 46 takes the ve measurement signals previously described, from lines 47, 49, 52 and 59, and computes from the individual rates and temperatures of the feed materials and the heat of reaction of said materials in said riser the conversion of hydrocarbon feed materials. Network 46 produces a single output signal, representative of this conversion.

This output signal is sent via line 77 to a conversion controller 23. A desired rate of hydrocarbon feed conversion is preset via set point 21 on controller 23, as determined by the product desired from the reactor system. Controller 23 compares the computer output signal 77 with the set point thereon, and obtains, by conventional means, a rst control signal, the magnitude lof which is related to the difference between the computer signal and set point. This control -signal is transmitted via line 22a to motor valve 17 to change the aperture thereof. The ow rate of the regenerated catalyst through 18 is thus automatically adjusted until the desired rate of hydrocarbon conversion, or depth of cracking, in riser 18 is attained. Increasing catalyst flow rate, increases the rate of conversion, and vice versa.

Similarly, the same signal from controller 23 can pass via line 22b to motor valve 79. Thus, a greater -or lesser quantity of regeneration air is admixed with the spent catalyst in transfer conduit 36 leading to regenerator 13, whereby the degree of catalyst regeneration is varied, until the desired catalyst activity or rate of hydrocarbon conversion is attained. Increasing regeneration air feed rate, will result in better burn oft of coke on the spent catalyst, and, in turn, greater catalyst activity in the riser and reactor. Either motor valve 17 or 79 may be operated` singly to manipulate the hydrocarbon conversion, simply by omitting the undesired motor valve. In a third embodiment, the control signal from controller 23 may adjust the motor valves concurrently.

In operation, all of the previously described temperature and pressure differential measurements are made and transmitted in analog form to the computing network. These signals are representative Iof the magnitudes of said variables `and other preselected data influencing and resulting from the operations of said reactor and said regenerator.

The conventional measurement and control equipment previously described are available from many automatic controller manufacturers utilizing pneumatic or electronic energy or combinations of the two as the analog of the measurement and control signals. Likewise, equipment capable of performing the calculations -given above is available in either pneumatic or electronic form, as desired, from several manufacturers. In most instances, complex automatic control and optimizing systems will use both pneumatic and electronic instrumentation, computation and control components to the best advantage. Measurement inputs and computing networks must be compatible in their analogies, therefore in some cases transducers from pneumatic to electrical signals, or vice versa, are required to achieve operability and mathemati-cal c-onsistency.

Conversion controller 23 and all other controllers shown are available from a choice of commercial units to perform this function. For example, there is the Foxboro M/40 controller described in Bulletin SA-lOA of November 1955 by the Foxboro Company, Foxboro, Massa-chusetts.

The calculation of the ow rate of the hydrocarbon feed (W0) moving into the riser, based on the measured pressure drop APo in feed conduit 24, is as follows:

WozKll/APO APO-pressure drop across oil feed orifice, lb./ft.2. Knzaccumulated constant for oil feed orifice and line 24.

The caluclation of the flow rate of the steam feed (Ws) moving into the riser, -based on the measured pressure drop across steam orice in line 25, is as follows:

APS-pressure drop across steam orice, lb./ft.2. Klozaccumulated constant for steam `oriiice and line 25.

The calculation of the ow rate of catalyst (We) in the riser, based on the measured pressure drop in riser 18, is as follows:

Catalyst flowztotal owmeasured flow of steam-measured ow of oil.

Total ow is determined from pressure drop across riser (APT) as measured by PL and PU.

Lzlength of riser, in feet. I/:velocity of carrier gas in riser, ft./sec. Vtztransport velocity of carrier, ft./sec. Kqzaccumulated constant to make V a direct function of APS, APT-pressure drop of feed materials in riser, lbs/ft2. KzKq/Kz.

Wt=K8(APs) 1'(APT) +K4(APT) -i-KAPsT/Ll-Ks (18) Catalyst How rate may now 'be calculated as follows:

Wc=Wt-WoWs (19) W C=flow rate of catalyst through riser, lbs./ sec. Wo=ow rate of oil into riser, lbs/sec. Wsziiow rate of steam into riser, lbs./sec.

Hydrocarbon conversion:

C HIN-HOUT 1b. oil cracked (1200) (Wo)- lb. oil feed wherein Wozflow rate of oil, 1b./see. C=conversion in riser.

l200=heat of reaction, B.t.u. absorbed per pound of oil cracked.

HIN=HCI+HOI+HSI=heat content of all materials entering riser.

H QUT-:HCO-l-Hpo-i-H so=heat content of all materials leaving riser.

Hpftw.) (SH.) (L1400).

TL=temperature in at bottom of riser, F.

T U=temperature out at top of riser, F.

Wt=total lb./ sec. moved through riser.

Ws=lb./sec. of steam feed.

Wo=lb./sec. of oil feed.

Wc=lb./sec. of catalyst moved through riser.

SH1=specic heat of catalyst at riser inlet, B.t.u./ (lb.)

SH2=specific heat of oil at riser inlet, B.t.u./(lb.) F.).

SH3=specitic heat of steam at riser inlet, B.t.u./ (lb.)

Sh24=specic heat of catalyst at riser outlet, B.t.u./(lb.)

SH 5=speeic heat of oil at riser outlet, B.t.u./ (lb.) F.). SHzspecic heat of steam at riser outlet, B.t.u./ (lb.)

F.). HCI=heat content of catalyst at riser inlet, B.t.u./sec. HSI=heat content of steam at riser inlet, B.t.u./sec. HOI=heat content of oil at riser inlet, B.t.u./sec. Hcozheat content of catalyst at riser outlet, B.t.u./see. Hs0=heat content of steam at riser outlet, B.t.u./sec. Hpo=heat content of product at riser outlet, B.t.u./sec. 700=datum temperature.

The utilization of these analog signals, representative of ve measured variable, wi-ll now be described in more detail in connection with computing network 46 of FIG- URE 2. The network is broken down into functional components. It should be understood, therefore, that the individual components of network 46 are not to be considered the invention, but rather it resides in the combination of these elements into a specific cooperation which permits the automatic vcomputation of a certain derived process variable, herein hydrocarbon conversion, and therefrom automatically adjusting the ow rate of regenerated catalyst to the reactor to the desired value or air rate to the regenerator, or both.

Referring now to FIGURE 2, measurement signals from lines 47, 49, 56, 52 and 59 are transmitted to network 46. The signal from line 49 passes to a square root extracting component 101. The resulting signa-l passes via lead 102 to a rst multiplying component 103, wherein it is multiplied by a second signal entering component 103 via line 52. This second multiplier signal is representative of the pressure drop across the riser. A third signal enters component 103. T-his third multiplier signal is the constant K8, defined previously, which is manually set as an input signal on terminal 104 of component 103. The product signal passes Via lead 106 to rst adding component 107.

The resulting signal from component 101 simultaneously passes via lead 108 to a second multiplying component 109, wherein said product is multiplied by a signal entering component 109. This multiplier signal is the constant K9, previously defined, which is manually set as an input signal on the terminal 111 of component 109. This product signal passes via lead 112 to adding component 107.

Input signal from lead 52 additionally passes via lead 113 to a multiplying component 114, wherein said signal is multiplied `by a signal entering component 114. This multiplier signal is the constant K4, previously defined, which is manually set as an input signal on the terminal 114t of component 114. This product signal passes via lead 11S to adding component 107. A fourth signal, K6, previously defined, is placed on terminal 107t of component 107, all of the signals being summed therein.

The resulting summed signal passes via line 116 to a second summing component 117, said signal being representative of the flow rate of the feed materials in the riser.

The resulting signal from component 101 passes via leads 102 and 118 to a fourth multiplying component 119, wherein said signal is multiplied by a signal entering com ponent 119. This multiplier signal is the constant Kw, previously defined, which is manually 4set as an input signal on the terminal 1191* of component 119. This product signal, with sign reversed, passes via lead 120 to summing component 117, serving as a iirst subtrahend therein.

A third input signal passes via lead 47 to a square root extracting component 121. The resulting signal passes via lead 122 to a fifth multiplying component 123, wherein it is multiplied by a signal entering component 123. This multiplier signal is the constant K11, previously defined, which is manually set as an input on the terminal 123t of component 123. This product signal, with sign reversed, passes via lead 1230 to summing component 117, serving as a second subtrahend therein.

The resulting second summed signal passes via line 124 to sixth multiplying component 125. This signal (WC), being representative of the flow rate of catalyst up the riser.

A fourth input signal 56, representative of the temperature of the feed materials in the lower end of the riser, passes to subtracting component 126 serving therein as the minuend. A signal, representative of the datum ternperature of 700 F. is manually set as an input on terminal 127 of component 126, serving as the subtrahend therein. The remainder signal passes therefrom via line 128 to multiplying component 125 to serve as a first multiplier signal therein. A second multiplier signal, the constant SHI, previously defined, is manually set as an input on the terminal 129 of component 125. This product signal passes via line 131 to a dividing component 132 wherein said product signal is divided by a signal entering component 132, which is manually set as an input on terminal 133 thereof. This divisor signal is representative of the value 1200, which is the heat of reaction, per pound of feed oil cracked, expressed in B.t.u.s. The quotient signal from component 132 passes via line 134 to third summing component 136.

The remainder signal from component 126 also passes via lines 137 and 138 to multiplying components 139 and 141, respectively. Regarding component 139, a second multiplier signal, the constant SH3, previously defined, is manually set as an input on the terminal 142 of component 139. A product signal from multiplying component 119 passes via lines 120 and 137 to multiplying component 139 to serve as a third multip-lier signal therein. This product signal passes via line 143 to a dividing component 144, wherein said product signal is divided by a signal entering component 144, which is manually set as an input on terminal 145 thereof. This divisor signal is again representative of the value of 1200. The quotient signal from component 144 passes via line 146 to summing component 136.

Regarding multiplying component 141, a multiplier signal, the constant SH2, previously defined, is manually set as an input on the terminal 147 thereof. A product signal from component 123 passes via lines 1230 and 148 to multiplying component 141 to serve therein as a second multiplier signal. This product signal passes via line 149 to a dividing component 151, wherein said product signal is divided by a signal entering component 151, which is manually set as an input on terminal 152 thereof. This divisor signal is again representative of the value of 1200. The quotient signal from component 151, passes via line 153 to summing component 136.

A fifth input signal 59, representative of the temperature of the feed materials, now partially cracked, in the "upper end of the riser passes to a subtracting component 156, serving therein as the minuend. A signal, representative of the datum temperature of 700 F. is manually set as an input on terminal 157 of component 156, serving as the subtrahend therein. This remainder signal passes via line 158 to multiplier component 159, to serve as a first multiplying signal therein. A second multiplying signal, the constant SH5, previously defined, is manually set as an input on the terminal 161 of component 159. The product signal from multiplying component 123 also passes via lines 1230 and 162 to multiplying component 159 to serve as a third multiplier therein. This product signal passes via line 163 to a dividing component 164, wherein said product signal is divided by a signal entering component 164, which is manually set on the input terminal 166 thereof. This divisor signal is the value 1200. The quotient signal from component 164 passes via line 167 to summing component 136, with a negative slgn.

The remainder signal from component 119 also passes via lines 120 and 168 to multiplying component 169, as a first multiplier signal. The remainder signal from component 156 also passes via lines 158 and 171 to multiplier component 169, as a second multiplier signal. A third multiplier signal, the constant SH6, previously defined, is manually set as an input on the terminal 172 of component 169. The product signal from multiplier component 169 passes via line 173 to a dividing component 174, wherein said product signal is dividedby a signal entering component 174, which is manually set on the input terminal 176 thereof. This divisor signal is the value of 1200. The quotient signal from component 174, passes via'line 177 to summing component 136, with a negative sign.

The first summed signal from summer 117 passes via lines 124 and 178 to multiplier component 180 to serve as a first multiplier signal therein. The remainder signal from component 156 also passes via lines 158 and 179 to multiplier component 180. A third multiplier signal, the constant SH4, previously defined, is manually set as an input on the terminal 181 of component 180. The product signal from component 182 passes via line 182 to a dividing component 183, wherein said product signal is divided by a signal entering component 183, which is manually set on the input terminal 184, thereof. This divisor signal is the value 1200. The quotient signal from component 183 passes via line 186 to summing component 136 with a negative sign.

The resulting third summed signal passes via line 187 to dividing component 188. This signal is representative of P, the pounds of oil cracked in the riser. A product signal from component 123, representative of the iiow rate of the oil feed, passes via lines 1230 and 189 to dividing component 188 to serve as the divisor therein. The quotient signal is representative of percent hydrocarbon conversion from component 188, passes via line 77 to conversion controller 23 of FIGURE l, wherein the control signals 22a and b are produced as previously described.

To lone skilled in the analog computing art, it will be obvious that in many cases several mathematical operations in FIGURE 2 may be combined in one piece of computing equipment, so that the apparent number of computing steps in an actual apparatus will be reduced.

We claim:

1. Apparatus comprising: a fluid catalytic cracking reactor having a variable reactor temperature and variable catalyst bed level; a catalyst regenerator; first conduit riser means communicating between said regenerator and said reactor for conducting hot regenerated catalyst into the latter; second conduit means for feeding hydrocarbon material to be cracked communicating with said first conduit riser means; third conduit means for feeding steam communicating with said first conduit riser means; fourth conduit means communicating between said reactor and said regenerator for conducting spent catalyst to the latter; fifth conduit means for feeding air to regenerate the owing spent catalyst communicating with said fourth conduit means; sixth conduit means communicating with the upper portion of said reactor for conducting reaction products and reacted feed material to a main fractionator; seventh conduit means communicating with the upper portion of said regenerator for conducting iiue gases to Vent; means for measuring the temperature of the feed materials flowing in said first conduit riser means in both the upstream and downstream portions of the latter; means for measuring the flow rate of said hydrocarbon material and said steam flowing in said second and third conduit means, respectively; means to measure the ow rate of said feed materials in said first conduit riser means; means for controlling the rate of flow of said regenerated catalyst disposed in said rst conduit riser means upstream of said second and third conduit means; a computer having a fixed program; first means within said computer for computing the total heat contents of said feed materials in both the lower and upper portions of said first conduit riser means; second means within said computer for computing from the last mentioned computations the weight of oil feed cracked per unit time while in said first conduit riser means; and third means within said computer for computing from the last mentioned computation the hydrocarbon conversion in said first conduit riser means and obtaining a derived signal representative thereof.

2. Apparatus comprising: a fluid catalytic cracking reactor having a variable reactor temperature and variable catalyst bed level; a catalyst regenerator; first conduit riser means communicating between said regenerator and said reactor for conducting hot regenerated catalyst into the latter; second conduit means for feeding hydrocarbon material to be cracked communicating with said first conduit riser means; third conduit means for feeding steam communicating with said first conduit riser means; fourth conduit means communicating between said reactor and said regenerator for conducting spent catalyst to the latter; fifth conduit means for feeding air to regenerate the fiowing spent catalyst communicating with said fourth conduit means; sixth conduit means communicating with the upper portion of said reactor for conducting reaction products and reacted feed material to a main fractionator; seventh conduit means communicating with the upper portion of said regenerator for conducting fiue gases to vent; eighth conduit means communicating with the bottom of said fractionator for conducting non-converted products back to said first conduit riser means; means for measuring the temperature of the feed materials flowing in said first conduit riser means in both the upstream and downstream portions of the latter; means for measuring the orifice differential pressures of said hydrocarbon material and said steam flowing in said second and third conduit riser means, respectively; means to measure the differential pressure of said materials in said first conduit means between an upstream point and a downstream point; means for controlling the rate of fioW of said regenerated catalyst disposed in said first conduit means upstream of said second and third conduit means; a computer having a fixed program; first means within said computer for computing the flow rate of said feed materials, collectively and individually, from the measured differential pressures; second means Within said computer for computing the total heat contents of said feed materials in both the lower and upper portions of said first conduit riser means; third means within said computer for computing from the last mentioned computations the weight of oil feed cracked per unit time while in said first conduit riser means; and fourth means within said computer for computing from the last mentioned computation the hydrocarbon conversion in said first conduit riser means and obtaining a derived signal representative thereof; conversion control means responsive to said derived signal for adjusting fiow control means disposed in each of said first conduit riser means and fifth conduit means to manipulate the fiow rate of regenerated catalyst and regeneration air, respectively, in order to vary reactor temperature, thereby regulating the hydrocarbon conversion to attain a preselected level.

3. Apparatus comprising: a fiuid catalytic cracking reactor having a variable reactor temperature and variable catalyst bed level; a catalyst regenerator; first conduit riser means communicating between said regenerator and said reactor for conducting hot regenerated catalyst into the latter; second conduit means for feeding hydrocarbon material to be cracked communicating with said first c-onduit riser means; third conduit means for feeding steam communicating with said first conduit riser means; fourth conduit means communicating between said reactor and said regenerator for conducting spent catalyst to the latter; fifth conduit means for feeding air to regenerate the flowing spent catalyst communicating with said fourth conduit means; sixth conduit means communicating with the upper portion of said reactor for conducting reaction products and reacted feed material to a main fractionator; seventh conduit means communicating with the upper portion of said regenerator for conducting fiue gases to vent; eighth conduit means communicating with the bottom of said fractionator for conducting non-converted products back to said first conduit riser means; means for measuring the temperature of the feed materials fiowing in said first conduit riser means in both the upstream and downstream portions of the latter; means for measuring the orifice differential pressures of said hydrocarbon material and said steam fiowing in said second and third conduit means, respectively; means to measure the differential pressure of said feed materials in said first conduit riser means at an upstream point and a downstream point; means for controlling the rate of flow of said regenerated catalyst disposed in said first conduit riser means upstream of said second and third conduit means; a computer having a fixed program; first means within said computer for computing the fiow rate of said feed materials, collectively and individually, from the measured differential pressures; second means within said computer for computing the total heat contents of said feed materials in both the lower and upper portions of said first conduit riser means; third means within said computer for computing from the last mentioned computations the weight of oil feed crackedper unit time while in said first conduit riser means; and fourth means within said computer for computing from the last mentioned computation the hydrocarbon conversion in said first conduit riser means; and obtaining a derived signal representative thereof; and conversion control means responsive to said derived signal for adjusting fiow control means disposed in said first conduit riser means to manipulate the fiow rate of regenerated catalyst in order to vary reactor temperature, thereby regulating the hydrocarbon conversion to attain a preselected level.

4. Apparatus comprising: a fiuid catalytic cracking reactor having a variable reactor temperature and variable catalyst bed level; a catalyst regenerator; first conduit riser means communicating between said regenerator and said reactor for conducting hot regenerated catalyst into the latter; second conduit means for feeding hydrocarbon material to be cracked communicating with said first conduit riser means; third conduit means for feeding steam communicating with said first conduit riser means; fourth conduit means communicating between said reactor and said regenerator for conducting spent catalyst to the latter; fifth conduit means for feeding air to regenerate the flowing spent catalyst communicating with said fourth conduit means; sixth conduit means communicating with the upper portion of said reactor for conducting reaction products and reacted feed material to a main fractionator; seventh conduit means communicating with the upper portion of said regenerator for conducting flue gases to vent; eighth conduit means communicating with the bottom of said fractionator for conducting non-converted products back to said first conduit riser means; means for measuring the temperature of the feed materials flowing in said first conduit riser means in both the upstream and downstream portions of the latter; means for measuring the orifice differential pressures of said hydrocarbon material and said steam flowing in said second and third conduit means, respectively; means to measure the differential pressure of said feed materials in said first conduit riser means at an upstream point and a downstream point; means for controlling the rate of flow of said regenerated catalyst disposed in said first conduit riser means upstream of said second and third conduit means; a cornputer having a fixed program; first means within said computer for computing the fiow rate of said feed materials, collectively and individually, from the measured differential pressures; second means within said computer for computing the total heat contents of said feed materials in both the lower and upper portions of said first conduit riser means; third means within said computer for computing from the last mentioned computations the weight of oil feed cracked per unit time while in said first conduit riser means; and fourth means within said computer for computing from the last mentioned computation the hydrocarbon conversion in said first conduit riser 1 1 means; and conversion control means responsive to said derived signal for adjusting flow control means disposed in fifth conduit means to manipulate the flow rate of regeneration air in order to vary reactor temperature, thereby regulating the hydrocarbon conversion to attain a preselected level.

5. A method for automatically measuring hydrocarbon conversion in the riser of a fiuidized catalytic reactor and controlling the depth of cracking of petroleum oils thereby in a catalytic cracking process responsive to a control signal calculated by a computer having a fixed program, comprising: producing a signal proportional to the individual rates of flow of the oil and steam feeds being introduced into a riser of a catalytic reactor; producing a signal proportional to the total feed material flow rate through said riser; measuring the temperature of said feed materials in the lower portion of said riser; determining by difference in flow rates of the total stream and the oil and steam feeds the flow rate of regenerated catalyst through said riser; measuring the temperature of said materials in the upper portion of said riser; producing a signal proportional to the total heat contents of said feed materials in both the lower and upper portions of said riser; producing a signal proportional to the heat absorbed by the reaction of said feed materials, producing a signal proportional to the hydrocarbon conversion in said riser to give a first signal; comparing said first signal to a constant second signal, representative of desired hydrocarbon conversion to obtain a control signal, the magnitude of which is related to the difference between said first and second signals; and adjusting both the iiow rate of the regenerated catalyst to said reactor and regeneration air to said regenerator responsive to said first control signal until hydrocarbon conversion in said riser attains a desired level.

6. The method according to claim 5 wherein the flow rate of regenerated catalyst is computed according to the equations:

WC=Wt-WOWS wherein Wt=liow rate of feed materials in riser, lbs./ sec.

W=flow rate of oil into riser, 1bs./ sec. Wszflow rate of steam into riser, lbs/sec.

7. The method according to claim wherein the unit weights of said oil feed cracked per unit time is computed according to the equations:

8. The method according to claim 5 wherein the hydrocarbon conversion in the riser is computed according to the equation:

wherein Wo=flow rate of oil into riser, lbs/sec.

9. A method for automatically measuring hydrocarbon conversion in the riser of a uidized catalytic reactor and controlling the depth of cracking of petroleum oils thereby in a catalytic cracking process responsive to a control signal calculated by a computer having a fixed program, comprising: measuring producing a signal proportional to the individual rates of flow of the oil and steam feeds v said riser; producing a signal proportional to the heat absorbed by the reaction of said feed materials, producing a signal proportional to the hydrocarbon conversion in said riser to give a first signal; comparing said first signal to a constant second signal, representative of desired hydrocarbon conversion to obtain a control signal, the magnitude of which is related to the difference between said first and second signals; and adjusting the flow rate of the regenerated catalyst to said reactor responsive to said first control signal until hydrocarbon conversion in said riser attains a desired level.

10. A method for automatically measuring hydrocarbon conversion in the riser of a iiuidized catalytic reactor and controlling the depth of cracking of petroleum oils thereby in a catalytic cracking process responsive to a control signal calculated by a computer having a fixed program, comprising: measuring the individual rates of flow of the oil and steam feeds being introduced into a riser of a catalytic reactor; producing a signal proportional to the total feed material flow rate through said riser; measuring the temperature of said feed materials in the lower portion of said riser; determining by difference in flow rates of the total stream and the oil and steam feeds the flow rate of regenerated catalyst through said riser; measuring the temperature of said materials in the upper portion of said riser; producing a signal proportional to signals the total heat contents of said feed materials in both the lower and upper portions of said riser; producing a signal proportional to the heat absorbed by the reaction of said feed materials, producing a signal proportional to the hydrocarbon conversion in said riser to give a first signal; comparing said first signal -to a` constant second signal, representative of desired hydrocarbon conversion to obtain a control signal, the magnitude of which is related to the difference between said first and second signals; and adjusting the flow rate of the regeneration air to said regenerator responsive to said first control signal until hydrocarbon conversion in said riser attains a desired level.

References Cited by the Examiner UNITED STATES PATENTS 2,982,717 5/61 Waddill 208-108 OTHER REFERENCES Automatic Control of Chemical Petroleum Process, Williams et al., chapter 7, pp. 207 to 270, Gulf Publishing Co., Houston, TeX., 1961.

The Use of Digital Computers in Petroleum Refining, by Hagler and Shea, vol. V of Advances in Petroleum Chemistry and Refining, pp. 124 to 129, Interscience Publishers, New York.

ALPHONSO D. SULLIVAN, Primary Examiner.

UNITED STATES PATENT OFFICE 53 CERTIFICATE OF CORRECTIGN Patent No. 3,213,014 v October 19, 1965 Robert G. Atkinson et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 9, line 31, after "said", first occurrence, insert feed column 11, line 65, strike out "measuring".

Signed and sealed this 27th day of September 1966.

(SEAL) Attest:

ERNEST W. SW'IDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

10. A METHOD FOR AUTOMATICALLY MEASURING HYDROCARBON CONVERSION IN THE RISER OF A FLUIDIZED CATALYTIC REACTOR AND CONTROLLING THE DEPTH OF CRACKING OF PETROLEUM OILS THEREBY IN A CATALYTIC CRACKING PROCESS RESPONSIVE TO A CONTROL SIGNAL CALCULATED BY A COMPUTER HAVING A FIXED PROGRAM, COMPRISING: MEASURING THE INDIVIDUAL RATES OF FLOW OF THE OIL AND STEAM FEEDS BEING INTRODUCED NTO A RISER OF A CATALYTIC REACTOR; PRODUCING A SIGNAL PROPORTIONAL TO THE TOTAL FEED MATERIAL FLOW RATE THROUGH SAID RISER; MEASURING THE TEMPERATURE OF SAID FEED MATERIALS IN THE LOWER PORTION OF SAID RISER; DETERMINING BY DIFFERENCE IN FLOW RATES OF THE TOTAL STREAM AND THE OIL AND STREAM FEEDS THE FLOW RATE OF REGENERATED CATALYST THROUGH SAID RISER; MEASURING THE TEMPERATURE OF SAID MATERIALS IN THE UPPER PORTION OF SAID RISER; PRODUCING A SIGNAL PROPORTIONAL TO SIGNALS THE TOTAL HEAT CONTENTS OF SAID FEED MATERIALS IN BOTH THE LOWER AND UPPER PORTIONS OF SAID RISER; PRODUCING A SIGNAL PROPORTIONAL TO THE HEAT ABSORBED BY THE REACTION OF SAID FEED MATERIALS, PRODUCING A SIGNAL PROPORTIONAL TO THE HYDROCARBON CONVERSION IN SAID RISER TO GIVE A FIRST SIGNAL; COMPARING SAID FIRST SIGNAL TO A CONSTANT SECOND SIGNAL, REPRESENTATIVE OF DESIRED HYDROCARBON CONVERSION TO OBTAIN A CONTROL SIGNAL, THE MAGNITUDE OF WHICH IS RELATED TO THE DIFFERENCE BETWEEN SAID FIRST AND SECOND SIGNALS; AND ADJUSTING THE FLOW RATE OF THE REGENERATION AIR TO SAID REGNERATOR RESPONSIVE TO SAID FIRST CONTROL SIGNAL UNTIL HYDROCARBON CONVERSION IN SAID RISER ATTAINS A DESIRED LEVEL. 